When a hardcopy device such as an inkjet printer is not in use, pigment in the ink in its printheads tend to be deposited around each printhead nozzle leaving relatively thin ink, i.e. with a higher proportion of solvent, in the nozzle itself. To avoid deterioration in print quality after a period of non-use, a servicing operation needs to be undertaken to ensure correct operation of the nozzle immediately on commencement of a subsequent printing operation. This typically involves wiping of the nozzle with an elastomeric wiper blade and the spitting of some drops of ink from the nozzle so that it contains ink of the required formulation. The wasted drops of ink are captured within a device known as a spittoon.
The spittoon needs to be of a size corresponding at least to the maximum amount of ink it is expected to contain. Disposing of ink waste materials from a printer usually poses problems regarding satisfactory containment, the danger of liquid spills and environmental considerations. Spittoons contain liquid or semi-liquid materials, and need to be handled with care by end users. Existing spittoons can be categorised as:                a) Permanent spittoons, in cases in which the total amount of ink waste is relatively limited over the lifetime of a printer. However, permanent spittoons are unsuitable where there is little space for storage and/or the predicted amount of ink waste is relatively high.        b) Disposable cleaning cartridges, in which a cartridge or cassette comprises a relatively small spittoon, a wiper and a printhead cap. The cartridge is designed to handle a given amount of waste ink, and is arranged to be replaced at intervals, typically at the same time as a corresponding printhead or other component. The size of the spittoon is selected in accordance with the expected amount of waste ink between being replaced.        c) Disposable service station, which is similar to category b) except that all the service station parts are replaced simultaneously. In practice, the service station is replaced independently of the printheads.        
The question of the removal of waste ink product becomes an increasing problem as the number of printhead nozzles increases, as a printer's duty cycles become heavier and as the proportion of pigment in modern inks increases. The problem directly affects such issues as spittoon size and replacement frequency but also the intervention rate, handling, liquids disposal and machine size.
To reduce the volume of the accumulated waste ink product, it is possible to collect it in solid form. U.S. Pat. No. 5,617,124 discloses a printer with a service station located at one end of the path of travel of a scanning printhead carriage, the service station incorporating a spittoon in the form of a rotating circular trough. Ink previously purged from the printheads is removed from the trough by a scraper and accumulated ink solids fall to the bottom of a spittoon chamber.
U.S. Pat. No. 6,340,220 discloses a printer service station arranged at one end of the path of a scanning printer. The service station comprises a spittoon wheel arranged with its axis parallel to the scanning axis of the printer and having a circumferential surface arranged to receive ink ejected from a printhead. Liquid components of ink waste are removed from the surface of the wheel, with the assistance of a scraper, into a temporary container from where solid ink residue is transferred to a further storage location.
Scanning type printers, as disclosed in the above-mentioned U.S. patents, are well known, in which printheads are mounted on a carriage which undertakes reciprocating movements between two end positions. A print medium moves underneath the printheads in a direction perpendicular to the direction of the carriage scanning movements. To undertake servicing operations with respect to the printheads, such as capping, wiping, priming and spitting, they are moved beyond one of the end positions to be located adjacent to a service station. This is time-consuming and a precise positioning system is required to ensure that the printheads are accurately returned to the correct printing position after a servicing operation has been undertaken.
This problem is avoided in a page-wide array type of printer, in which one or more fixed printheads extend over the entire width of the printing path. However, undertaking a servicing operation on the printheads again required a precise positioning system to allow the various printer components to move between their printing and servicing configurations.
U.S. Pat. No. 5,081,472 discloses a service station for a page-wide array printer. The service station comprises a rotatable drum which can be pivoted from a servicing position into a position where it is clear of the printhead to permit a printing operation.
Co-pending U.S. patent application Ser. No. 10/426,574 discloses a hardcopy device comprising a drum platen having a circumferential surface for supporting print media as they move relative to one or more print bars, the circumferential surface also comprising an axially-extending recessed area constituting a spittoon arrangement for the print bars. The contents of this co-pending application are hereby incorporated by reference.